It is proposed to study the role of cyclic AMP and protein phosphorylation in normal and abnormal brain function and in the mechanism of action of antipsychotic drugs. A main approach is the study of the properties of a cyclic AMP-dependent protein kinase discovered in the brains of several mammalian species. The possibility will be investigated that psychotropic drugs may exert their behavioral effects by indirectly affecting protein phosphorylation. The possible role of cyclic AMP-dependent protein phosphorylation will be studied in three areas: (a) in mediating the postsynaptic effects of neurotransmitters; (b) in regulating tyrosine hydroxylase activity; and (c) in regulating neurotransmitter release. BIBLIOGRAPHIC REFERENCES: Liu, A.Y.-C., and Greengard, P. (1976) Regulation by steroid hormones of phosphorylation of specific protein common to several target organs. Proc. Nat. Acad. Sci. U.S.A. 73: 568-572. Greengard, P. (1976) Possible role of cyclic nucleotides and phosphorylated membrane proteins in postsynaptic actions of neurotransmitters. Nature 260:101-108.